Continuous tube forming and galvanizing



Jan- 25, 1966 T. H. KRENGEL ETAL 3,230,615

CONTINUOUS TUBE FORMING AND GALVANIZING DISCHARGE/ United States Patent 3,230,615 y CONTINUOUS TUBE FORMING AND GALVANIZING Theodore H. Krengel, Chicago, and Emil Wilk, Park Forest, Ill., assiguors to Allied Tube & Conduit Corporation, Blue Island, Ill., a corporation of Illinois Filed Nov. 23, 1962, Ser. No. 239,432 Claims. (Cl. 29-200) This invention is a continuation-impart of our copending applications Ser. No. 106,699, led May 1, 1961, and entitled Continuous Tube Forming and Galvanizing, now Patent No. 3,122,114, dated February 25, 1964.

This invention relates to a process and apparatus for the continuous forming and galvanizing of thin wall metal tubing and it relates more particularly to the production of finished and sized galvanized thin wall tubing from metal strip.

It is an object of this invention to produce improvements in the method and apparatus described and claimed in the aforementioned copending application for the continuous forming and galvanizing of thin wall steel tubing from continuous strip.

More specifically, it is an object to provide a number of improvements in processing steps and equipment which are effective (1) to improve the quality and characteristics of the galvanizing operation; (2) to improve the safety of the continuous operation in the forming and galvanizing process; (3) to improve the speed of operation whereby a higher yield is secured per unit length of time; (4) to improve the preparation of the metal for the welding and galvanizing of the formed metal strips; ('5) to improve the operation of forming the metal strip into tubing and the processing thereof in the welding and galvanizing operations, and (6) to improve the eiliciency and operation of the system whereby less interferences are encountered in the conduct of the forming and galvanizing in a continuous process.

rthese and other objects' and advantages of this invention will hereinafter appear and for purposes of illustration; but not of limitation, embodiments of the invention are shown in the accompanying drawings, in which- FIG. lis a flow diagram of .the continuous forming and galvanizing of thin wall tubing from metal strip;

FIG. 2 is a schematic sectional elevational view of an additional processing step interposed between the scarf and the wash;

FIG. 3 is a schematic view in cross-section showing the air knife immediately following the galvanizing step;

FIG. 4 is an elevational view of the air knife shown in FIG. 3; and y FIG. 5 is an elevational view of a modication in FIG. 4 showing the combination of air knives which may be employed in the removal of excess zinc and in the control of the' amount thereof:A allowed to remain on the tubing'. Before entering into-a description of the'improvements embodying the features of this invention', reference will be made to the method and apparatus for the continuous forming and galvanizing of metal strip, as described and claimed in the aforementioned copending application.

Brieliy described, the metal strip 10 is unrolled from reels 12 mounted for rotational movement on a stand 14. The strip is advanced through suitable end-joining and 3,230,615 Patented Jan. 25, 1966 FCice take-up means 16 to 44 to an edge shave 46 wherein the lateral edges of the strip are trimmed to size the strip and to present freshly cut metal to the subsequent operation for welding after the edges are brought together by the tube forming rolls 48.

rom the edge trimmer 46 the strip is advanced through a wiper 47 and into the bank of forming rolls'48 wherein the strip is formed to tubular shape.

From the forming rolls 48, the tubing is advanced through a weld section including a seam Welder 5t), a seam` shaver 52, a water cooling spray 53, and a Welder 54 to produce a welded tubing 56 which is subsequently advancedl through washers 58 and 74, a rinse 78' and acid wash 80, followed by a water rinse 96 for the removal ofoxide, grease, etc. from the surface of the metal tubingV in preparation of the tubing for the subsequent galvaniz-n ing operation.

The welded and cleaned tubing 56 then proceedscontinuously from the cleaning section toa steam blast 97- for the removal of surface moisture and then to induction' heaters for preheating the formed tubing to a temperaturek suitable for entry into the bath 132 of moltenzinc for galvanizing. The preheat and the housing containing the molten zinc is maintained under an inert atmosphe're to minimize oxidation and to enhance theV galvanizing operation.

At the outlet from the housi'ng 132 containingv the molten zinc, a die system is embodied for the removal of excess molten zinc from the' surface and thereafter the galvanized tubing 56 is advance/d througha water spray` 164 for freezing the zinc onto the surface of the steel tubing. From there, the galvanized tubing is put through water spray section19'0 for coolingv d-ow4 the tubing before being advanced to the marking roll 191,. sizing rolls 192 and traveling shears 194 wherein they galvanized tubing is sized to the desired length for use.

Having described the arrangement of processing stepsand equipment, description' will now be" made' in the specific modifications and improvements embodying fea` tures of this invention. Such improvements have t'o do with separate segments ofthe process and apparatus which combine for the continuous forming and galvanizing of thin wall tubing but description thereof will be taken up inthe order in which they originally arise in the combination-ot process steps and equipment.

A problem that has 'been encountered in the process of continuous forming and galvanizing of steel tubing resides inthe difficulty experienced properly to galvanize the outer surfaces of the formed tubingl 'to provide a uniform and continuous coating of zinc wherever small amounts of iro-n oxide remain on the surface.

Such small amounts of oxide are to be found alongside the'sc-arf 522L upon removal of the prctru-dingportion of the bead 19C formed during the welding. Such oxides. illustrated by the numeral 52h, are not effectively removed during the subsequent washing and pickling `steps to which the formed tubing is exposed after welding but before preheat and galvanizing.

Further, the oxides present on the surfaces of the formed tubingA have been found to catalyze the formation of additional oxidation products as well asl other reaction products when the metal is raised to elevated temperature in the preheat.

It has been found that the continuous tube forming and galvanizing process is markedly enhanced and that the uniformity and quality of product is greatly improved when the surface of the tubing, including the scarfed portions and the portions adjacent thereto, is engaged by the periphery of a rapidly rotating wire bristle brushing wheel 52c which is preferably mounted and operated for rotational movement in a direction whereby the periphery of the wheel travels countercurrent to the direction of movement of the tubing, thereby to maximize engagement and effect. For this purpose, the wire brushing Wheel 52c is mounted on a spindle 52d in position to engage the top side of the formed tubing subsequent to the scariing operation but before the Washers and acid pickling. The spindle is ySupported in suitable journals 52e in engagement with a drive shaft of a driving motor 52f. Thus the oxides remaining in the scarf and the portions adjacent thereto are removed to present a surface free of oxides to the preheat and galvanize.

Another concept of this invention is addressed to an improved means for setting the zinc on the surface of the tubing to achieve a desired thickness of coating and for removal of excess zinc from the surface of the tubing. In accord-ance with the lpractice of this invention, use is made of a doughnut 200 in the form of an annular ring having `a central opening 202 through which the tubing 56 is advanced immediately following emergence from the bath of molten zinc an-d after the galvanized tubing has passed from within the closure 132..` The annular ring 260 is provided with a plurality of jet openings 204 which face inwardly and rearwardly .and are uniformly distributed inlsubstantially equally spaced apart relation about the inner periphery of the ring to direct air streams 206 inwardly and rearwardly onto the surfaces of the tubing.

The air streams function as air knives to cu-t olf excess zinc and rearwardly to displace `such excesses onto the surfaces of the oncoming tubing thereby to insure adequate'and complete coverage while excess molten zinc 208 drops from the tubing into -a suitable underlying receiver 210 which leads from the outside of the housing to the interior thereof 'for return of zinc to the molten bath.

In the modificati-on shown in FIG. 12, use is made of an additional ring 212 located rearwardly of the ring 200 and which is also provided with a central opening 214 in axial alignment with the opening Ztl@ in the ring 200 through which the tubing 56 is advanced. The additional ring 212 is also provided with a plurality of openings 216 which are addressed inwardly and forwardly to direct streams of cold air onto the periphery of the tubing in advance of the cut-E ring 200. The cold air from the ring 212 operates to freeze the zinc onto the surfaces of the tubing in a manner to cause a heavier layer of zinc to resist removal by the air knife ring 200 whereby a heavier layer 21S of zinc is retained on the surface. By controlling the amount of air and the temperature of the air, the thickness of the layer 218 of retained zinc can be varied in accordance with the specification or demands for particular uses. It will be understood that more than one jet cooling ring 212 can be employed in series before the cut-olf ring 200 to insure the retention and proper distribution of the desired amount of zinc in the layer 21S that is retained on the surface.

It will be understood that numerous changes may be made in the details of construction, arrangement and operation Without departing from the spirit of the invention, especially as defined in the following claims.

' We claim:

1. In a machine for the continuous forming and 'galvanizing of tubing from metal strip, including means for continuously feeding the metal strip to the machine, means for forming the strip to rounded shape to bring the later-al edges together, welding means for joining the free edges of the metal strip in a continuous seam to form completely enclosed endless lengths of tubing7 scarfing means for removing portions of the weld extending outwardly beyond the periphery of the tubing, means for preheating the tubing to a temperature suitable for wetting with molten zin-c, means for applying molten zinc onto the surface of the preheated tubing and means for cutting the endless Zinc coated tubing into predetermined lengths, the improvement which comprises a wire bristle brushing wh-eel located in alignment with the line of travel of the tubing beyond the scarting means but in advance of the preheat means and radially positioned with respect to the axis of the tubing to bring the edges of thewire bristles of the wheel into engagement with a peripheral portion of the formed and welded tubing which includes the scarfed wheel and the portions immediately adjacent thereto, and means for rotating the Wire bristle brush to'bring the bristles into brushing engagement with the peripheral surface of the formed tubing to remove oxides from the engaged surfaces.

2. A machine as claimed in claim 1 in which the wire bristle brush is located in a -direction for movement of the 'bristles counter-current to the direction of movement of the tubing.

3. In a machine for the continuous forming and galvanizing of tubing including means for continuously Ifeeding endless strips of steel, means for forming the steel strip into rounded shape to bring the lateral edges together, welding means for joining the free edges of the strip of steel in a continuous seam to form completely enclosed endless lengths of tubing, means for applying molten zinc onto the outer surface of the tubing to galvanize the outer surface and means for cutting the galvanized tubing into predetermined lengths, the improvement which comprises means for controlling the amount of zinc retained on the outer peripheral surface of the tubing comprising a first ring having a central opening aligned with the tubing beyond the means for applying lmolten zinc for passage of the zinc coated tubing therethrough and immediately following said zinc coating means, a plurality of orifices in the inner portion of the ring for directing streams of gas in a direction rearwardly and inwardly onto the oncoming surface of the tubing and arranged to engage the tubing all around with the issuing gaseous streams for displacement of excess molten Zinc from the peripheral surface of the tubing, and an additional ring between the lirst ring and the zinc coating means, said additional ring being axially aligned with the rst ring `and having a central opening for the passage of the tubing therethrough, a plurality of orifices located in the inner periphery of the additional ring for addressing streams of gas forwardly and inwardly in the direction of movement of the tubing and onto the periphery thereof to cool the zinc sufliciently to increase the thickness of the layer of zinc retained on the tubing.

4. In a machine for the continuous forming and galvanizing of tubing including means for continuously feeding endless strips of steel, means for forming the steel strip into rounded shape to bring the lateral edges together, welding means for joining the free edges of the strip of steel in a continuous seam to form completely enclosed endless lengths of tubing, means for applying molten zinc onto the outer surface of the tubing to galvanize the outer surface and means for cutting the galvanized tubing into predetermined lengths, the improvement which comprises means for controlling the amount 4of zinc retained lon the outer peripheral surface of the tubing comprising a tirst ring having a central opening aligned with the tubing beyond the means for applying molten zinc for passage of the zinc coated tubing therethrough and immediately following said zinc coating means, a plurality of orifices in the inner portion of the ring for directing streams of gas in a direction rearwardly and inwardly onto the oncoming surface of the tubing and arranged to engage the tubing all around with the issuing gaseous streams for displacement of excess molten zinc from the peripheral surface of the tubing, and an additional ring between the first ring and the Zinc coating means, `said additional ring being axially aligned with the first ring land having a central opening for the passage of the tubing therethrough, a plurality of orifices located in the inner periphery of the additional ring for addressing streams of gas forwardly and inwardly in the direction of movement of the tubing and onto the periphery thereof to cool the zinc sufficiently to increase the amount of zinc that resists displacement by the first ring.

References Cited bythe Examiner UNITED STATES PATENTS Lloyd 113-33 Greenfield 118-63 Pritchard 118-63 Obert 113-12 Hays 113-33 Sonnichsen 219-59 Johnson 219-59 FOREIGN PATENTS 5. A machine as claimed in claim 3 in which the gas 15 CHARLES W- LANHAM, Primary Examiner- WILLIAM J. STEPHENSON, Examiner.

is cool air. 

1. IN A MACHINE FOR THE CONTINUOUS FORMING AND GALVANIZING OF TUBING FROM METAL STRIP, INCLUDING MEANS FOR CONTINUOUSLY FEEDING THE METAL STRIP TO THE MACHINE, MEANS FOR FORMING THE STRIP TO ROUNDED SHAPE TO BRING THE LATERAL EDGES TOGETHER, WELDING MEANS FOR JOINING THE FREE EDGES OF THE METAL STRIP IN A CONTINOUS SEAM TO FORM COMPLETELY ENCLOSED ENDLESS LENGTHS OF TUBING, SCARFING MEANS FOR REMOVING PORTIONS OF THE WELD EXTENDING OUTWARDLY BEYOND THE PERIPHERY OF THE TUBING, MEANS FOR PREHEATING THE TUBING TO A TEMPERATURE SUITABLE FOR WETTING WITH MOLTEN ZINC, MEANS FOR APPLYING MOLTEN ZINC ONTO THE SURFACE OF THE PREHEATED TUBING AND MEANS FOR CUTTING THE ENDLESS ZINC COATED TUBING INTO PREDETERMINED LENGTHS, THE IMPROVEMENT WHICH COMPRISES A WIRE BRISTLE BRUSHING WHEEL LOCATED IN ALIGNMENT WITH THE LINE 